The present invention relates to a weight detecting device which is mounted in an automatic heating and cooking apparatus such as an electronic oven, etc. for use in detecting the weight of a food to be heated or cooked.
The weight of a food is an extremely important and useful factor for cooking, together with vapor and/or gas generated from the food, when the automization of cooking is going to be realized. Particularly, in the technical field of the electronic oven, the automization of cooking has been established through detection of the weight of the food by the use of a weight sensor, and this technique of the automatic cooking has been already practiced, for example, when automatically defrosting frozen foods.
Meanwhile, the weighing errors due to the difference in the position where the food or the like to be measured is placed are a common problem in any weight detecting devices including the weight sensor of the electronic oven. For avoiding such influences by the weighing errors as above, therefore, for example, the weight sensor of the electronic oven disclosed in international publication WO 87/04786 (SAKAMOTO et al.) employs a weighing system called Roberval's system which works to transmit the load of an object to be measured correctly to a weight detecting means wherever the objects is placed on a weighing platform in the sensor. As shown in FIG. 6, the load of the object is effectively transmitted in a thrust direction with respect to a shaft 22. Therefore, it is not necessary for a user of the weight sensor to place the object in a designated position on the platform, but the correct weight of the object can be detected whenever the object is placed on the platform.
The Roberval's mechanism although it is remarkably useful in practical use as described above, is generally complicated and bulky structure, as seen from FIG. 6. Moreover, from the characteristic viewpoint, since the system's efficiencies will be effectively brought out as the space in the thickness direction is increased, the system is inevitably large in size. Thus, the presence of the Roberval's mechanism in the weight sensor is contradictory in itself to the improvement of efficiencies, resulting in an obstacle to designing a space-saving, thinner weight sensor.